1. Field of the Invention
The present invention relates to a resistive composition to be used for a resistor to detect electric currents that flow in the current detecting circuits or the like, a resistor using the same, and a making method thereof.
2. Description of the Related Art
For the purpose of detecting electric currents that flow in the electronic circuits and/or power circuits of an equipment or the like, resistors having low resistance value and low temperature coefficient of resistance (TCR) have been needed. Such resistors have used resistive element such as silver (Ag)-palladium (Pd), copper (Cu)-nickel (Ni), or copper-manganese (Mn) alloy so as to obtain the low resistance characteristic, as disclosed in, for example, Laid-open Japanese Patent Application Nos. 8-83969 and 9-213503.
A current detecting chip resistor, which uses as a resistive composition copper-nickel alloy, copper-manganese-tin (Sn) based alloys, copper-manganese-germanium (Ge) based alloys, or the like, and which controls deterioration of electric current detection accuracy due to the resistor temperature variation, has been proposed and, for example, is disclosed in Laid-open Japanese Patent Application No. 2002-50501.
However, in the case of the above-mentioned copper-nickel composition resistive element, since the intrinsic property of copper, namely, its resistance value and the TCR (temperature coefficient of resistance) is dominant, the TCR increases as the resistance value decreases. Additionally, there is a problem with the copper-manganese resistor that its intrinsic resistance value varies. Due to this, the resistive paste cannot obtain the desired property (electric current detection precision).
Furthermore, in the case of the above-mentioned copper-nickel resistive element, since its electric resistivity is high, (0.65 μΩm), there is a problem where it is impossible to attain the recently demanded resistance value.
For example, when the copper-nickel composition is 60:40, the sheet resistance is 35 mΩ/□, and the TCR is 50×10−6/K. Additionally, when the copper-nickel composition is 90:10, the sheet resistance is 15 mΩ/□, and the TCR is 1200×10−6/K.
This invention is provided by taking the above-mentioned problems into account; its objective is to provide a low TCR resistive composition having low resistance value, a resistor using the same, and making method thereof